Mechanisms of Synergistic Removal of Low Concentration
As(V) by nZVI@Mg(OH)<sub>2</sub> Nanocomposite
- Publication date
- Publisher
Abstract
In
this work, by using Mg(OH)<sub>2</sub> nanoplatelets as support
material for nanoscale zerovalent iron (nZVI), nZVI@Mg(OH)<sub>2</sub> composite was prepared and found to have super high adsorption ability
toward As(V) at environmentally relevant concentrations. It was revealed
that the variation of corrosion products of nZVI in the presence of
Mg(OH)<sub>2</sub> and Mg<sup>2+</sup> is an important factor for
increase in the adsorption ability toward As(V). X-ray diffraction
(XRD) analysis indicated that the weakly basic condition induced by
Mg(OH)<sub>2</sub> decreases the lepidocrocite (γ-FeOOH) and
increases the magnetite/maghemite (Fe<sub>3</sub>O<sub>4</sub>/γ-Fe<sub>2</sub>O<sub>3</sub>) content in the corrosion products of nZVI,
and the latter has better adsorption affinity to As(V). Moreover,
extended X-ray absorption fine structure spectroscopy (EXAFS) indicated
that the coordination between arsenic and iron minerals is influenced
by dissolved Mg<sup>2+</sup>, leading to probable formation of magnesium
ferrite (MgFe<sub>2</sub>O<sub>4</sub>) which has considerable adsorption
affinity to As(V). This work provides an important reference not only
for the design of pollution control materials but also for understanding
arsenic immobilization in natural environments with ubiquitous Mg<sup>2+</sup> ion